I just joined this site, so I'm a little late to the game. I just read through this thread and found it quite interesting. Just a quick background on me:
I'm in sales/fleet department now at a Volvo and Mazda dealership. I've been in sales for 14 years total. I've sold Honda's (nest to Buick, Cadillac and GMC's) for 11 years. I've owned several Jeeps now, but not all in a row. With that said....
About the size of the new Compass, it's extremely close to the size of the Mazda CX5. I personally own a 2016 Jeep Patriot, and even that is similar in size to the CX5, CRv, and Toyota Rav4. The Mazda CX3 is a much smaller vehicle and is based on the Mazda2 sold in Japan and sold in the USA under Toyota as the I-A (formerly Scion). The HRv is a little smaller too, but I don't know as much about that because I didn't sell it.
In terms of MPG's, I don't care how you slice it or which brand. It all comes down to how you drive, your tire pressure, air filter, driving conditions, etc. It really makes me laugh when I hear people talk about Honda and Toyota being so good on fuel. I have a friend who drives a Honda Pilot and a GMC Sierra Duramax and his truck gets better MPG's. Personally, I keep my vehicle well kept and the tires are checked monthly and kept at the suggested pressure. My Patriot is the 2.4L, front drive with the 6 speed auto. If I'm not using the A/C and I drive nice, I will get just a tick over 31mpg. Under normal every day driving in mostly city with a couple highway miles in the mix, I will average 22 mpg. Again, I currently sell Mazda's and I will guarantee you the CX5 drivers are not getting anything above that. Most are averaging around 25 total.
For anyone thinking about buying the Mazda CX5, I can personally attest to how they drive and feel. I deliver cars for the fleet/internet department and I've put well over a thousand miles on the new 2017's. Although they are much more quiet than the old CX5, it still falls short in many areas. Getting comfortable in one is nearly impossible due to the ergonomics are so bad. In training, I've spent time in the Honda/Toyota's as well, and the Mazda is at least better than those two mainly because Mazda refuses to use the CVT trans! Thank goodness for that!
At the end of the day, I can't tell you how many times I get out of the Mazda and walk to my Patriot to go home. I get in and can't believe how much more I like it than driving the CX5. But hey, that's just me.